In a UMTS (Universal Mobile Telecommunications System) network, long-term evolution (LTE) is under study for the purposes of further increasing high-speed data rates, providing low delay and so on (non-patent literature 1). In LTE, as multiple-access schemes, a scheme that is based on OFDMA (Orthogonal Frequency Division Multiple Access) is used in downlink channels (downlink), and a scheme that is based on SC-FDMA (Single Carrier Frequency Division Multiple Access) is used in uplink channels (uplink).
Also, successor systems of LTE (referred to as, for example, “LTE-advanced” or “LTE enhancement” (hereinafter referred to as “LTE-A”)) are under study for the purpose of achieving further broadbandization and increased speed beyond LTE. In LTE-A (Rel. 10), carrier aggregation (CA), whereby a plurality of component carriers (CCs), in which the system band of the LTE system is one unit, are grouped to achieve broadbandization, is used. Also, in LTE-A, a HetNet (Heterogeneous Network) structure to use interference coordination technology (eICIC: enhanced Inter-Cell Interference Coordination) is under study.